BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	cntrycode,
	count(*) as numcust,
	sum(c_acctbal) as totacctbal
from
	(
		select
			substr(c_phone, 1, 2) as cntrycode,
			c_acctbal
		from
			customer
		where
			substr(c_phone, 1, 2) in
				('13', '24', '15', '12', '19', '28', '18')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('13', '24', '15', '12', '19', '28', '18')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                             QUERY PLAN                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692380.29..692380.29 rows=3 width=20) (actual time=11330.939..11330.941 rows=7 loops=1)
   Sort Key: (substr((customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=245811 read=80282
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52945.29..52945.30 rows=1 width=4) (actual time=520.881..520.881 rows=1 loops=1)
           Buffers: shared hit=35286 read=1058
           ->  Bitmap Heap Scan on customer customer_1  (cost=6655.40..51987.73 rows=383022 width=4) (actual time=94.627..445.846 rows=382212 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,24,15,12,19,28,18}'::text[])) AND (c_acctbal > 0::double precision))
                 Heap Blocks: exact=35278
                 Buffers: shared hit=35286 read=1058
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6559.65 rows=383022 width=0) (actual time=85.998..85.998 rows=382212 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{13,24,15,12,19,28,18}'::text[]))
                       Buffers: shared hit=10 read=1056
   ->  HashAggregate  (cost=639434.92..639434.97 rows=3 width=20) (actual time=11330.880..11330.882 rows=7 loops=1)
         Group Key: substr((customer.c_phone)::text, 1, 2)
         Buffers: shared hit=245808 read=80282
         ->  Hash Anti Join  (cost=595451.58..638988.12 rows=59574 width=20) (actual time=10621.360..11305.591 rows=63385 loops=1)
               Hash Cond: (customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=245808 read=80282
               ->  Bitmap Heap Scan on customer  (cost=2912.16..41870.75 rows=140213 width=24) (actual time=583.752..1099.330 rows=190604 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,24,15,12,19,28,18}'::text[])) AND (c_acctbal > $0))
                     Heap Blocks: exact=35170
                     Buffers: shared hit=35297 read=36762
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2877.10 rows=140213 width=0) (actual time=575.143..575.143 rows=190604 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{13,24,15,12,19,28,18}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35295 read=1594
               ->  Hash  (cost=404477.52..404477.52 rows=15044952 width=4) (actual time=9147.130..9147.130 rows=15015000 loops=1)
                     Buckets: 16777216  Batches: 1  Memory Usage: 658944kB
                     Buffers: shared hit=210508 read=43520
                     ->  Seq Scan on orders  (cost=0.00..404477.52 rows=15044952 width=4) (actual time=0.022..4498.818 rows=15015000 loops=1)
                           Buffers: shared hit=210508 read=43520
 Planning time: 2.741 ms
 Execution time: 11347.747 ms
(34 rows)

COMMIT;
COMMIT